Spot welder



SPOT WELDER Filed April 29, 194-2 lltll k wuwwtc o 2 MELVIN M. A. SEELQFF Patented Dec. 21, 1943 SPOT WELDEB Melvin M. A. Seelofl', Warren, Ohio, assignor to r The Taylor-Winfield Corporation,

Warren,

01110, a corporation oi Ohio Application April 29, 1942, Serial No. 440,942 (c1. era-4) 8 Claims.

This invention relates to electric resistance welding apparatus of the press or spot welding type and more particularly to improved methods and arrangements for moving and'applying welding pressure through the movable electrode of such apparatus. v v a The function of the electrode operating mechanism of a press or spot welder is to first bring the electrodes into engagement with the work posiing element moves'in proportion to the movement of the movable electrode and tends to move at uniform speedyeither'the electrode closing movemachine which operates in such manner that the r I with the work and upon completion of this closing movement. the welding pressure is smoothly and uniformly applied without any'substantial electrodes are quickly brought into engagement without encountering any substantial change in its resistance to movement. This materially increases the ease of operation of the machine as ell as reducing the wear and tear on the parts pivotally supported a rocker arm I2.

machine, by employing a coupling between an operating element of the primary moving means and the electrode carrying member which is operative at the start of the cycle of movement of the element to translate its movement into quick movement of the member and to thereafter translate the further movement of the element into the required welding force or pressure. Thus but a portion of the total travel of the element, which may be considered as the foot treadle in a manual vmachine, is employed to efi'ect the closing of the electrodes onto the work while a substantial part of the travel is employed to eifect the welding pressure. 4

The above and other objects and advantages of the invention will become apparent upon consideration of the following detailed specification and the accompanying drawing wherein there is specifically disclosed a preferred embodiment of the invention.

In the drawing:

Figure 1 is a side elevation of the upper portion 01' a manually operated spot welder constructed in accordance with the principles of the invention, certain 01 the electrical apparatus of the welder being shown schematically; and

Figure 2 is a plan on an enlarged scale of a portion of the apparatus of Figure 1.

In the drawing, reference numeral I 0 indicates a housing or pedestal on the top of which is secured spaced ears II on and between which is Extending outwardly of the rocker arm l2 and carried block 15 on which is adjustably mounted a bracket l7 carrying an electrode holder I8 similar to the electrode holder l3. Holder l8 supports the normally fixed electrode i9. As is well understood in the art, the housing In encloses the welding transformer shown schematically at 20 arm 12 to make electrical connection with the arm and/or holder l3. Block i6 is insulated from the frame or housing of the machine and consequently from the bracket l2 and holder l3. On the end of arm I2 opposite holder, l3 there 2,337,302 V v I is pivote a bellcrank lever 22, one leg of which foot treadle moves the flatter portion tlof'the is bifurcated to rotatably mount a camiollowing cam under the follower 23 so that the welding roller 23, while the other leg thereof is pivotally pressure isapplied without any substantial inconnected to a yoke 24. The pin making the last crease in resistance being encountered in the mentioned connection extends outwardly of one 5 downward movement of the foot treadle. It

' ed that welding current cannot side of the yoke to mount a member 25 into should be observ which is screwed a bolt 28. flow through the electrodes until the lever begins Pivotallymounted on a bracket 21 s to rotate with respect to the arm l2 and the the toner housing l il'is a bellcranklever 2$;one spring 38 begins to compress. Consequently the leg 29 of whi'ch is p'rwided withanenphe'rereem 1Q; welding current cannot be an" lied until a predesurface having a steep portion 30 and a flatter termine'dpressure, as governedby the initial exend portion 3|. As shown in Figure 1, the,= :ca rn;;.- pansive force exerted by the spring 38, is exerted 30, 3| is engaged by the follower 23, a s ri er on the work by the electrodes. This pressure insuring the constant contact between the cam may be varied by adjusting the nuts 39 as will and follower. The spring 3 a r beunderstood. function of normally maintai ,theele t It"should now be apparent that I have 'pro- M and I9 in spaced open relation reg electrode moving mechanism for spot the length of the holders [g and i3, qonn gt q welders which accomplishes the objects ini- .with the other leg of tne"1et'r zaisa t'odfis 'tially s'et -butliE-But a small portion of the total which is moved upwardly by the pivotally-mou t 2Q t rav el of the foot treadle is required to bring the h a meme with us al ele rodes into engagement with the work while e" 'th" nine travelis: resolved into he IOngeroremai ater'iiorce multiplication to l effect 7 the weldi ngpressure and thei;r equired co'mpression of es i d n pr s u pp ngz iii manne-r-othemwelderl is-p made much e operate, uniform results are attained, and by Li'ieasomiohthe elemination of undue'stress and 19 is shock :in any; ,ofy th e op ative parts, lessrnainok e Zdan'dl'ocked 30 e s'- e uire.da s

Rod as :is anlt should.zbeiund rs -th a h ovejspe nding through difically 1-:de r b d-1,emb m imap "th th, rig'idly atta'ched i nisiil u t a ve y sinc v ous y a y nii esis isositiond beoc ane mar hes eade there nawithout depart- 1mg; from-;the-;-;spirit 1 ontscope of ,the i'nvention.

at. .uReference sho ld therefore; be had". to the appended, claims in; deterrniningthelscope' of the 'nvention."

V m' 2;. 1: 1: Q r

-:manu re a ed t pid eld jrilc mpr ing a norn' ally f xed electrod 'al' movable elec- 1 v ro ke 3 ;rrn; supporting said Imovable electrode for,- movement toward" and away from t d to rock ,saidarm comprisinga i H 4 r d can; and alcam i ollower connected; w .said. farm; id cam havin a steep portionto efiecta quick closing movement of I the electrodes, onto the work positioned--,therebe tween, nd' a .flatte'ri portion to efi ect Qweldirig (pressure '1 between said,v electrodes upon completion or'seic' closing movement;

A manu ly operated'lspotwelder comprisxed electroda fla movable elecber, idjustably mounting? said moving a no m troda a e1 twee er movement toward and away fiXed'electr'Io de, meiinsftp, m ve, said g "member comp"'s'ingfa' manuially operated cam tion of meter-re ,7 a anmow r; ennee aw tnsa 4i Wei h switch v in actual practicef 'oprates aid" cain having steep ortion I to fiect 'r e as-i welllundelr'stood iii the 3117.550 arq 'k' closirig l vement bi the electrodes onto the'letiddesil4" the ,tvorkf.positioned, vtherebetween; and a fiatth both terfportion, ,tofefie tjwiumg pressure between F esu onfcomplet" "fgsaidclosing ntrols "he not s d electrod W rodsf fjthefworl; said secondmember will'i r'riove relative to said first" mentioned member "upon "the application of *a' "predetermined orce mosaic second mentioned meinber, means said element and during movement thereof through but a portion of its path travel a quick closing movement of theelectrodes onto the work positioned therebetween 6. Welding apparatus comprising in combi nation a normally fixed electrode. a movable 'adjustably mounting sa d movable electrode for movement toward and fixed OICCIludG, a bellcrank lever pivoted on said arm, a yieldable connection beand said arm, a cam portion of less pitch adjacent the outer end of the said other leg, and means to maintain said follower in contact with said cam.

MELVIN M. A. SEELOFF. 

